The letter posted on Israeli journalist Amit Segal channel to 184,000 followers says that “the nation of Israel will stand up bravery to strike at its enemies,” according to a translation of the Hebrew. It goes on to justify targeting sites even “when the enemy hides behind a human shield.”
That’s asymmetric warfare for you, if hamas operated like Israel and had bases out in the open they’d be annihilated in a week. Israel would probably do the same if hamas had overwhelming air superiority.
Most Palestinians don’t support Hamas but most do support armed resistance, mostly because every other form of resistance has been taken away from them. That’s why they were voted in in 2006, and if Israel does succeed then whoever takes over after will probably just as militant, unless Israel gives them some other way to effectively protest mosque raids and west bank settlements.